Damaged or rotted railroad ties must be removed from and replaced in an existing rail bed. To replace such ties, the spikes holding the tie fixed with respect to its associated rails must be removed and any ballast, gravel or other debris in the vicinity of the tie must also be removed.
Conventionally, track is jacked up over the tie to create additional clearance to permit removal of the tie. Once the spikes have been removed, the ballast has been removed and the track has been jacked up, the tie is conventionally pulled by one or more track workers bending over and manually extracting the tie by pulling it along its longitudinal direction, transversely to the rails.
Various mechanized approaches have been suggested for removing railroad ties but heretofore none have any significant degree of acceptance, much less commercial success. Typical of the mechanized approaches are those shown in U.S. Pat. Nos. 1,247,224 and 4,343,457 which disclose rail jack apparatus designed to apply some mechanical advantage to a tie being removed from a rail bed. The apparatus disclosed in these patents has not been adopted or used to any significant degree, let alone been commercially successful, in part because the apparatus necessitates that the track, from which the tie is being removed, be taken out of operation during the tie removal process. On busy roadbeds, this unacceptable.
Of the prior art known to applicant, of greatest relevance to the invention is U.S. Pat. No. 2,133,851 disclosing tie pulling apparatus which can be used to remove a tie while not presenting any obstruction to safe and normal passage of a train over the rails under which the tie is being removed and replaced. However, for a variety of reasons, the apparatus disclosed in '851 has not been accepted and track workers have continued to rely on manual methods, with associated obvious danger of disabling back injury. One probable reason that the '851 apparatus has not achieved any significant acceptance, let alone commercial success, in the railway maintenance field is that the '851 apparatus cannot be used to remove a worn, damaged or rotted tie and to insert a replacement tie without either moving the apparatus (with respect to the position into which the tie is to be inserted) while replacing the tie or interfering with tracks adjacent to the track undergoing repair.
Other reasons the '851 apparatus has not achieved commercial acceptance are that the apparatus is cumbersome to move and is difficult to place into and maintain in position and in engagement with the railroad track under which a tie is being replaced.